Removing Western Australia's Disability Services Commission director-general while changes to the NDIS are underway is like sacking a coach before the grand final, the state opposition says.
Opposition leader Mike Nahan said the National Disability Insurance Scheme was in complete chaos because the state government failed to allocate resources and dismissed Ron Chalmers, who was the "leading light" and architect of NDIS in WA, at a cost of more than $400,000.
"He understood the system and his task was to bed it down over the next year," Dr Nahan told reporters on Thursday.
"This is like firing the coach right before a grand final match.
"Retirement was not too far off. This was his last hurrah."
Dr Nahan said as a result, it was likely WA would be penalised for failing to meet agreed key performance indicators, programs would be delayed and services would be more expensive.
But a spokeswoman for Disability Services Minister Stephen Dawson said Mr Chalmers chose to leave earlier than requested.
"Mr Chalmers made the decision to leave his position in July and the Minister for Disability Services requested that he remain until August," she said.
"The Director General's departure will not affect the roll out of the NDIS, which has been well planned and considered. The agency has a plan in place and will implement that plan accordingly."
Nulsen Disability Services chief executive Gordon Trewern declined to comment on Dr Nahan's view, but said Mr Chalmers had done a brilliant job as a director-general during a difficult time.
Mr Trewern said he was keen to get behind the new amalgamated department and backed WA having control over its own system.
"We believe that's fundamentally important," he told AAP.
He said the national model was a great idea, but it had been rushed.
The state government is slashing the number of departments from 41 to 25, with some senior public servants taking redundancies or being axed, which has been heavily criticised by the opposition.
Among those leaving are Road Safety Commissioner Kim Papalia and Department for Child Protection director-general Emma White.
Dr Nahan urged the state government to come clean about the cost of redundancies, which he estimated would be at least $25 million if 20 per cent of senior executives were culled.